Method for forming fine pattern having variable width and method for manufacturing semiconductor device using the same

ABSTRACT

A method for forming a fine pattern having a variable width by simultaneously using an optimal focused electron beam and a defocused electron beam in a light exposure process Includes, after forming a first film on a substrate, forming a first film pattern including a first level area and a second level area having different distances from the substrate by changing a profile of an upper surface of the first film. A photoresist film having a first area covering the first level area and a second area covering the second level area is formed. To simultaneously light-expose the first area and the second area with the same width, a light exposure condition, in which an optimal focused electron beam is eradiated on the first area and a defocused electron beam is eradiated on the second area, is applied. A plurality of photoresist patterns continuously extending over the first level area and the second level area with different widths on the first level area and the second level area are formed by developing the light-exposed photoresist film.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit under 35 U.S.C. 119 of Korean PatentApplication No. 10-2009-0131836, filed on Dec. 28, 2009, in the KoreanIntellectual Property Office, the entire content of which isincorporated herein by reference.

BACKGROUND

The inventive concept relates to a method for forming a fine patternhaving a variable width in a semiconductor device and a method formanufacturing a semiconductor device having the same, and moreparticularly, to a method for variably forming a width of each patternwhen simultaneously forming a plurality of patterns having a fine pitchand a method for manufacturing a semiconductor device using the same.

In manufacturing of highly scaled high-density semiconductor devices,when simultaneously forming a plurality of fine patterns separated fromeach other with a fine interval, there are situations in which someareas of the plurality of fine patterns must be formed with an increasedwidth in comparison to other areas, depending upon the requirements of aunit device to be formed. To form a plurality of fine patterns includingsome areas having an increased width, a photolithography process isperformed using a photo mask on which is formed a light exposure patterncorresponding to a shape to be finally formed on the device. In thephotolithography process, if any of the intervals between some areashaving the increased width and their neighboring fine patterns is toonarrow such as to be over a resolution limit of the photolithographyprocess, it is difficult to form a fine pattern having a desired form.

Accordingly, in situations in which a plurality of fine patternsseparated from each other with a fine interval are formed to have avariable width in a length direction, a technique is needed for easilyforming a fine pattern having a desired form even when the interval istoo narrow such as to be over the resolution limit of thephotolithography process.

SUMMARY

The inventive concept provides a method for forming a fine pattern, inwhich, in cases where a plurality of fine patterns separated from eachother with a fine interval are formed to have a variable width in alength direction, a pattern having a desired form may be simply andeasily formed, even when the interval is too narrow such as to be over aresolution limit of a photolithography process being used.

The inventive concept also provides a method for manufacturing asemiconductor device, in which, in manufacturing a semiconductor devicehaving a unit device including a plurality of fine patterns separatedfrom each other with a fine interval and having a variable width in alength direction, a manufacturing process of Ultra Large ScaleIntegration (ULSI) semiconductor devices including fine patterns may besimplified by simply and easily forming a pattern having a desired form,even when the interval between the plurality of fine patterns is toonarrow such as to be over a resolution limit in a photolithographyprocess.

According to an aspect of the inventive concept, there is provided amethod for forming a fine pattern, the method including: forming a firstfilm on a substrate; forming a first film pattern including a firstlevel area and a second level area having different distances from thesubstrate by changing a profile of an upper surface of the first film;forming a photoresist film having a first area covering the first levelarea and a second area covering the second level area; light-exposingthe photoresist film under a light exposure condition, in which anoptimal focused electron beam is eradiated on the first area and adefocused electron beam is eradiated on the second area, by using aphoto mask having a light exposure pattern for simultaneouslylight-exposing the first area and the second area with the same width;forming a plurality of photoresist patterns continuously extending overthe first level area and the second level area of the first film patternwith different widths on the first level area and the second level areaby developing the light-exposed photoresist film; and forming aplurality of first fine patterns having different widths on the firstlevel area and the second level area by etching the first film patternusing the plurality of photoresist patterns as an etching mask.

The forming a first film pattern may include: forming a mask patterncovering an upper surface of the first film; forming a recess part witha bottom surface having a level lower than that of the upper surface ofthe first film by etching a portion of the first film from the uppersurface of the first film using the mask pattern as an etching mask; andexposing an upper surface of the first film pattern by removing the maskpattern.

The bottom surface of the recess part may be disposed in the first levelarea, and the upper surface of the first film pattern may be disposed inthe second level area. Alternatively, the bottom surface of the recesspart may be disposed in the second level area, and the upper surface ofthe first film pattern may be disposed in the first level area.

The method may further include forming a second film having an uppersurface with a floor level difference on the first film pattern beforeforming the photoresist film and after forming the first film pattern.In this case, the photoresist patterns may be formed on the second film.The second film may be a single film or a multiple film in which aplurality of films are layered in order.

In the method, a plurality of first level areas may be included on theupper surface of the first film pattern. The first level area may have aplanar structure of a form of a plurality of lines extending parallel toeach other.

Alternatively, a plurality of first level areas may be included on theupper surface of the first film pattern. Each of the plurality of firstlevel areas may have a planar structure of one of a circle, an ellipse,and a polygon.

The substrate may include a first member layer exposed on an uppersurface thereof. The method may include forming a first member patternhaving a variable width in a length direction by etching the firstmember layer using the first fine pattern as an etching mask afterforming the first fine pattern. The first member layer may be aninsulation film or a conductive film.

According to another aspect of the inventive concept, there is provideda method for manufacturing a semiconductor device, the method including:forming a conductive layer on a substrate; forming a hard mask layer onthe conductive layer; changing a profile of an upper surface of the hardmask layer so that a first level area and a second level area havingdifferent distances from the substrate are included on an upper surfaceof the hard mask layer; forming a photoresist film having a first areacovering the first level area of the hard mask layer and a second areacovering the second level area of the hard mask layer on the hard masklayer; light-exposing the photoresist film under a light exposurecondition, in which an optimal focused electron beam is eradiated on thefirst area and a defocused electron beam is eradiated on the secondarea, by using a photo mask having a light exposure pattern forsimultaneously light-exposing the first area and the second area withthe same width; forming a plurality of photoresist patterns continuouslyextending over the first level area and the second level area of thehard mask layer with different widths on the first level area and thesecond level area by developing the light-exposed photoresist film;forming a plurality of hard mask patterns having different widths on thefirst level area and the second level area by etching the hard masklayer using the plurality of photoresist patterns as an etching mask;and forming a plurality of conductive patterns having a variable widthin a length direction by etching the conductive layer using theplurality of hard mask patterns as an etching mask.

On the substrate, the first level area of the hard mask layer may have alevel lower than that of the second level area of the hard mask layer.

In the light-exposing the photoresist film, the light exposure patternof the photo mask may include a light-projecting area having a form of aplurality of lines extending in the same direction with a constant widthand a light-shielding film pattern having a form of a plurality of lineslimiting the light-projecting area.

The substrate may include a conductive area, and the plurality ofconductive patterns may include a plurality of contact areas contactingthe conductive area. Each of the plurality of contact areas included inthe plurality of conductive patterns may have a width wider than thoseof the other parts of the plurality of conductive patterns. Each of theplurality of conductive patterns may constitute a bit line of asemiconductor device.

Alternatively, the substrate may include an isolation area and an activearea defined by the isolation area, the plurality of conductive patternsmay continuously extend over the active area and the isolation area onthe active area and the isolation area, and a part disposed on aboundary between the active area and the isolation area of the substrateout of the plurality of conductive patterns may have a width wider thanthose of the other parts of the plurality of conductive patterns. Eachof the plurality of conductive patterns may constitute a word line of asemiconductor device.

According to another aspect of the inventive concept, there is provideda method for manufacturing a semiconductor device, the method including:forming a mold layer on a substrate; forming a first film on the moldlayer; forming a first film pattern including a first level area and asecond level area having different distances from the substrate bychanging a profile of an upper surface of the first film; forming aphotoresist film having a first area covering the first level area and asecond area covering the second level area on the first film pattern;light-exposing the photoresist film under a light exposure condition, inwhich an optimal focused electron beam is eradiated on the first areaand a defocused electron beam is eradiated on the second area, by usinga photo mask having a light exposure pattern for simultaneouslylight-exposing the first area and the second area with the same width;forming a plurality of photoresist patterns continuously extending overthe first level area and the second level area of the first film patternwith different widths on the first level area and the second level areaby developing the light-exposed photoresist film; forming a plurality offirst fine patterns having different widths on the first level area andthe second level area by etching the first film pattern using theplurality of photoresist patterns as an etching mask; forming aplurality of mold patterns separated from each other with a plurality ofspaces by etching the mold layer using the plurality of first finepatterns as an etching mask; and forming a plurality of wiring patternsin the plurality of spaces.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other features and advantages of the inventive conceptwill be apparent from the more particular description of preferredembodiments of the inventive concept, as illustrated in the accompanyingdrawings in which like reference characters refer to the same partsthroughout the different views. The drawings are not necessarily toscale, emphasis instead being placed upon illustrating the principles ofthe inventive concept. In the drawings, the thickness of layers andregions may be exaggerated for clarity.

FIGS. 1A to 1H are partial perspective views illustrated in accordancewith a sequence of process steps, to illustrate a method for forming afine pattern according to a first exemplary embodiment of the inventiveconcept.

FIG. 2 is a partial top view illustrating a photo mask on which a lightexposure pattern applicable in a light exposure process is formed in themethod for forming a fine pattern according to the first exemplaryembodiment of the inventive concept.

FIGS. 3A and 3B are sectional views illustrating an incident area of anelectron beam in a partial area of a photoresist film on which anoptimal focused electron beam is eradiated and a partial area of aphotoresist film on which a defocused electron beam is eradiated inlight exposure in the method for forming a fine pattern according to thefirst exemplary embodiment of the inventive concept.

FIG. 4 is a top view illustrating a photoresist line pattern obtainedafter developing a photoresist film including an area on which anoptimal focused electron beam is eradiated and an area on which adefocused electron beam is eradiated in light exposure and a first filmpattern exposed through the photoresist line pattern in the method forforming a fine pattern according to the first exemplary embodiment ofthe inventive concept.

FIG. 5 is a top view illustrating a plurality of first fine patternsformed by the method for forming a fine pattern according to the firstexemplary embodiment of the inventive concept.

FIGS. 6A and 6B are top views illustrating a method for forming a finepattern according to a second exemplary embodiment of the inventiveconcept.

FIG. 7 is a layout of a plurality of fine patterns formable by applyinga method for forming a fine pattern according to a third exemplaryembodiment of the inventive concept.

FIGS. 8A to 8H are sectional views illustrated in accordance with asequence of process steps to illustrate the method for forming a finepattern according to the third exemplary embodiment of the inventiveconcept.

FIG. 9 is a layout illustrating a top view of a mask pattern applied inthe method for forming a fine pattern according to the third exemplaryembodiment of the inventive concept.

FIG. 10 is a layout illustrating a light exposure area of a photoresistfilm including an area on which an optimal focused electron beam iseradiated and an area on which a defocused electron beam is eradiated inlight exposure in the method for forming a fine pattern according to thethird exemplary embodiment of the inventive concept.

FIG. 11 is a layout of a plurality of fine patterns to be formed by amethod for forming a fine pattern according to a fourth exemplaryembodiment of the inventive concept.

FIGS. 12A to 12H are sectional views illustrated in accordance with asequence of process steps to illustrate the method for forming a finepattern according to the fourth exemplary embodiment of the inventiveconcept.

FIG. 13 is a layout illustrating a top view of a mask pattern applied inthe method for forming a fine pattern according to the fourth exemplaryembodiment of the inventive concept.

FIG. 14 is a layout illustrating a light exposure area of a photoresistfilm including an area on which an optimal focused electron beam iseradiated and an area on which a defocused electron beam is eradiated inlight exposure in the method for forming a fine pattern according to thefourth exemplary embodiment of the inventive concept.

FIG. 15 is a layout of a plurality of wiring patterns to be formed by amethod for forming a fine pattern according to a fifth exemplaryembodiment of the inventive concept.

FIGS. 16A to 16J are sectional views illustrated in accordance with asequence of process steps to illustrate the method for forming a finepattern according to the fifth exemplary embodiment of the inventiveconcept.

FIG. 17 is a layout illustrating a top view of a mask pattern applied inthe method for forming a fine pattern according to the fifth exemplaryembodiment of the inventive concept.

FIG. 18 is a layout illustrating a light exposure area of a photoresistfilm including an area on which an optimal focused electron beam iseradiated and an area on which a defocused electron beam is eradiated inlight exposure in the method for forming a fine pattern according to thefifth exemplary embodiment of the inventive concept.

FIG. 19 is a top view of a result after a plurality of photoresistpatterns are formed in the method for forming a fine pattern accordingto the fifth exemplary embodiment of the inventive concept.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The inventive concept will now be described more fully with reference tothe accompanying drawings, in which exemplary embodiments of theinventive concept are shown. The inventive concept may, however, beembodied in many different forms and should not be construed as beinglimited to the embodiments set forth herein; rather, these embodimentsare provided so that this description will be thorough and complete, andwill fully convey the inventive concept to those skilled in the art. Itwill be understood that when a layer is referred to as being “on”another layer or substrate, it may be directly on the other layer orsubstrate, or intervening layers may also be present. Various elementsand areas in the drawings are schematically drawn. Therefore, theinventive concept is not limited by a relative size or interval drawn onthe drawings.

FIGS. 1A to 1H are partial perspective views illustrated in accordancewith a sequence of process steps to illustrate a method for forming afine pattern according to a first exemplary embodiment of the inventiveconcept.

Referring to FIG. 1A, a first film 110 is formed on a substrate 100.

The substrate 100 may be formed of materials used to fabricate asemiconductor device. For example, the substrate 100 may be a siliconsubstrate. Alternatively, the substrate 100 may have a structureincluding a silicon substrate and unit devices needed to fabricate asemiconductor device, such as a transistor, a wiring layer, and aninsulation film, on the silicon substrate.

The first film 110 may have a flat upper surface 110T. The first film110 may include various materials depending upon the type of pattern tobe realized using the first film 110. For example, the first film 110may be an insulation film or a conductive film.

Referring to FIG. 1B, a mask pattern 120 is formed on the first film110. FIG. 1C illustrates a situation in which the mask pattern 120includes a plurality of line patterns extending in a first direction,e.g., the y direction in FIG. 1B). However, the mask pattern 120 mayhave various shapes. The mask pattern will be described below in moredetail with reference to FIGS. 6A and 6B. A portion of the upper surface110T of the first film 110 is exposed through the mask pattern 120.

The mask pattern 120 may include materials having a different etchingselectivity ratio from that of the first film 110. For example, the maskpattern 120 may be a photoresist. Alternatively, the mask pattern 120may be a hard mask pattern including an oxide, a nitride, or acombination of them.

Referring to FIG. 1C, a recess part 110R having a bottom surface 110U ata level lower than that of the upper surface 110T of the first film 110is formed by etching a portion of the first film 110 from the exposedupper surface 110T of the first film 110 using the mask pattern 120 asan etching mask.

Referring to FIG. 1D, the upper surface 110T of a first film pattern110A is exposed by removing the mask pattern 120.

By forming the recess part 110R on the first film 110, a profile of theupper surface 110T of the first film 110 is changed, resulting informing an uneven shaped topology including a first level area LV1 and asecond level area LV2 having different distances from an upper surfaceof the substrate 100 on the first film pattern 110A. In the currentembodiment, the first level area LV1 may be an area in which the recesspart 110R of the first film pattern 110A is disposed. The second levelarea LV2 may be an area other than the recess part 110R of the firstfilm pattern 110A, i.e., an area in which the upper surface 110T isdisposed.

A distance from the upper surface of the substrate 100 to a bottomsurface 110U of the recess part 110R is shorter than a distance from theupper surface of the substrate 100 to the upper surface 110T of thefirst film pattern 110A. A distance difference ΔD between the uppersurface 110T of the first film pattern 110A and the bottom surface 110Uof the recess part 110R may be predetermined as desired.

Referring to FIG. 1E, a photoresist film 130 is formed on the first filmpattern 110A.

In the current embodiment, there is illustrated a case in which thephotoresist film 130 includes positive photoresist materials. However,the inventive concept is not limited to this, and negative photoresistmaterials may be used.

Referring to FIG. 1F, using a photo mask having a predetermined lightexposure pattern, a portion of the photoresist film 130 is exposed to alight source.

FIG. 2 is a partial top view illustrating a photo mask 200 on which alight exposure pattern 220 according to an embodiment applicable in alight exposure process is formed, with reference to FIG. 1F.

In the photo mask 200 illustrated in FIG. 2, the light exposure pattern220 may include a light-projecting area 224 having a form of a pluralityof lines extending in the same direction with a constant width W1 on atransparent substrate 210 and a light-shielding film pattern 226 havinga form of a plurality of lines limiting the light-projecting area 224.

FIG. 1F shows light exposure areas 132 on the photoresist film 130 in acase of exposing the photoresist film 130 to a light source by means ofa light exposure process using the photo mask 200 illustrated in FIG. 2.

As illustrated in FIG. 1F, the plurality of light exposure areas 132 onthe photoresist film 130 may extend in a direction, e.g., the xdirection in FIG. 1F, orthogonal to an extended direction (y directionin FIG. 1F) of the recess part 110R. Thus, the plurality of lightexposure areas 132 on the photoresist film 130 may be designed tosimultaneously include the first level area LV1 in which the recess part110R is formed and the second level area LV2 in which the recess part110R is not formed. For a light exposure condition of the photoresistfilm 130, a light exposure condition in which an optimal focusedelectron beam is eradiated on the first level area LV1 and a defocusedelectron beam is eradiated on the second level area LV2 is applied. Todo this, an optimal focus position in light exposure of the photoresistfilm 130 may be set to the bottom surface 110U of the recess part 110R.By doing this, an optimal focused electron beam may be eradiated on thefirst level area LV1, and a defocused electron beam may be eradiated onthe second level area LV2 having the upper surface 110T of a levelhigher than that of the bottom surface 110U of the recess part 110R.

FIGS. 3A and 3B are sectional views illustrating an incident area of anelectron beam eradiated in a light exposure process, taken along cutlines IIIA-IIIA′ and IIIB-IIIB′ of FIG. 1F, respectively.

FIG. 3A schematically shows a section profile of an area on which anelectron beam is incident in the first level area LV1 out of the lightexposure areas 132 of the photoresist film 130 after the light exposureprocess described with reference to FIG. 1F. FIG. 3B schematically showsa section profile of an area on which an electron beam is incident inthe second level area LV2 out of the light exposure areas 132 of thephotoresist film 130 after the light exposure process described withreference to FIG. 1F.

In an area on which an optimal focused electron beam is eradiated out ofthe light exposure areas 132 of the photoresist film 130, i.e., firstareas 132-1 disposed on the first level area LV1 having the recess part110R, the electron beam in light exposure is evenly eradiated up to thebottom of the photoresist film 130 all over the light exposure areas132. However, in second areas 132-2 disposed on the second level areaLV2 on which a defocused electron beam is eradiated out of the lightexposure areas 132 of the photoresist film 130, the electron beam inlight exposure is not evenly incident in the light exposure areas 132due to a relatively poor focus, and the closer from the top of thephotoresist film 130 to the bottom thereof, the more areas 134 on whichthe electron beam is not eradiated in parts adjacent to non-lightexposure areas exist. The areas 134 on which the electron beam is noteradiated may be areas under slopes represented with dotted lines inFIG. 3B.

Referring to FIG. 1G, a photoresist line pattern 130A is formed bydeveloping the light-exposed photoresist film 130.

FIG. 4 is a top view showing the photoresist line pattern 130A obtainedafter performing a process of FIG. 1G and the first film pattern 110Aexposed through the photoresist line pattern 130A.

As illustrated in FIG. 4, the photoresist line pattern 130A includes aplurality of line patterns extending over the first level area LV1 andthe second level area LV2 and having a first width W1 on an uppersurface of the first level area LV1 and a second width W2 wider than thefirst width W1 on an upper surface of the second level area LV2.

Referring to FIG. 1H, a plurality of first fine patterns 110B are formedby etching the first film pattern 110A using the photoresist linepattern 130A as an etching mask. Thereafter, the photoresist linepattern 130A is removed.

FIG. 5 is a top view showing the plurality of first fine patterns 110Bobtained after performing a process of FIG. 1H.

As illustrated in FIG. 5, the plurality of first fine patterns 110B hasa variable width in a length direction (x direction in FIGS. 1H and 5)by having a first width LW1 in a y direction in the first level area LV1and having a second width LW2 wider than the first width LW1 in the ydirection in the second level area LV2.

In the method for forming a fine pattern according to the firstexemplary embodiment of the inventive concept described with referenceto FIGS. 1A to 5, there is illustrated a situation in which the bottomsurface 110U of the recess part 110R formed on the first film patter110A in the first level area LV1 has a planar structure of a form oflines extending in the y direction. However, the inventive concept isnot limited to this. For example, the bottom surface 110U of the recesspart 110R formed in the first level area LV1 may have an arbitrary planeform, such as a circle, ellipse, or polygon. To do this, a recess partof a desired form may be formed on the first film 110 by forming a maskpattern having a pattern of the desired form instead of the mask pattern120 as a mask pattern to be used as an etching mask on the first film110.

FIGS. 6A and 6B are top views illustrating a case of forming a recesspart of which a plane form is a rectangle on the first film 110according to a sequence of process steps in accordance with a method forforming a fine pattern according to a second exemplary embodiment of theinventive concept.

In FIGS. 6A and 6B, like reference numerals in the first embodimentdescribed with reference to FIGS. 1A to 5 denote like elements.

Referring to FIG. 6A, a mask pattern 620 having an opening 620H of whicha plane form is a rectangle is formed on the upper surface 110T of thefirst film 110 formed by the same method as described with reference toFIG. 1A. The opening 620H of the mask pattern 620 is formed to exposethe first level area LV1 of the first film 110.

Referring to FIG. 6B, a first film pattern 610A, on which a recess part610R having a rectangular plane form is formed, is formed by etching aportion of the total thickness of the exposed first film 110 using themask pattern 620 as an etching mask.

A distance difference (corresponding to Δ D of FIG. 1D) between a bottomsurface 610U of the recess part 610R and the upper surface 110T of thefirst film pattern 610A may be predetermined as desired.

Thereafter, a fine pattern may be formed from the first film pattern610A by performing the same processes as described with reference toFIGS. 1E to 1H and 2 to 5.

The first exemplary embodiment with reference to FIGS. 1A to 5 and thesecond exemplary embodiment with reference to FIGS. 6A and 6B illustratecases in which the recess part 110R or 610R is formed in the first levelarea LV1 of the first film 110, a photoresist film is formed on thefirst film pattern 110A or 610A, an optimal focused electron beam iseradiated on the bottom surface 110U or 610U of the recess part 110R or610R which is a surface of a relatively low level of the first filmpattern 110A or 610A, and a defocused electron beam is eradiated on theupper surface 110T of a relatively high level.

However, the inventive concept is not limited to this. According to aparticular application, a fine pattern having a wider width in thesecond level area LV2 rather than the first level area LV1 may be formedfrom the first film 110 by forming a recess part to form a bottomsurface of a lower level in the second level area LV2 of the first film110 so that a relatively high level remains on the upper surface 110T inthe first level area LV1, forming a photoresist film thereon, eradiatingan optimal focused electron beam on the photoresist film on a top of thefirst level area LV1 disposed relatively distant from the substrate 100,i.e., the upper surface 110T of the first film 110, and eradiating adefocused electron beam on the photoresist film on the second level areaLV2 in which a bottom surface of a relatively low level exists.

That is, according to the inventive concept, after a photoresist film isformed on an etched film, an optimal focused electron beam may beeradiated on a portion of a relatively high level of an upper surface ofthe etched film, and a defocused electron beam may be eradiated on aportion of a relatively low level of the upper surface of the etchedfilm, according to a form of a pattern to be formed and a designcondition. In any case of the embodiments, for a final fine patternobtained from the etched film, a width of a portion formed in an area onwhich a defocused electron beam is eradiated may be wider than a widthof a portion formed in an area on which an optimal focused electron beamis eradiated.

FIG. 7 is a layout of a plurality of fine patterns formable by applyinga method for forming a fine pattern according to a third exemplaryembodiment of the inventive concept.

FIG. 7 illustrates a case in which the plurality of fine patterns are aplurality of bit lines 750 formed in a cell array area of asemiconductor memory device.

Referring to FIG. 7, the plurality of bit lines 750 to be formed by amethod according to the inventive concept extend parallel to each otherin a predetermined direction (x direction in FIG. 7) on a semiconductorsubstrate. Below the plurality of bit lines 750 on the semiconductorsubstrate, a plurality of word lines 710 extend in a direction (ydirection in FIG. 7) orthogonal to the plurality of bit lines 750.

A plurality of direct contacts 720 are formed between two neighboringword lines 710. The plurality of direct contacts 720 are formed toelectrically connect an active area of the semiconductor substrate andthe plurality of bit lines 750 between them.

Because of an increase of density of semiconductor devices, to embody ahighly scaled device, each line width BW1 of the plurality of bit lines750 is becoming increasingly narrow. Each interval between the pluralityof bit lines 750 is also getting narrower. The more the density of asemiconductor device increases, the more contact dimensions between eachdirect contact 720 and a corresponding bit line 750 are reduced.Accordingly, to increase the contact dimensions between each directcontact 720 and a corresponding bit line 750, as illustrated in FIG. 7,it is desirable that the plurality of bit lines 750 be formed to have awidth BW2, wider than other portions in a portion contacting theplurality of direct contacts 720 out of the plurality of bit lines 750.In this case, when a light exposure process is performed by producing aphoto mask modified to reflect a form of the plurality of bit lines 750having the width BW2 increased in some areas, if the plurality of bitlines 750 are repetitively formed with a fine sized pitch smaller than aresolution limit of a photolithography process, in a part having theincreased width BW2 out of the plurality of bit lines 750, an interval Sbetween the part and each neighboring bit line 750 is too small, andthus, since light may not properly penetrate a part corresponding toeach interval S of the photo mask in light exposure, it is difficult toobtain a form of a desired pattern.

In the inventive concept, the plurality of bit lines 750 having thepartially increased width BW2 may be formed in a similar fashion to themethod for forming a fine pattern described with reference to FIGS. 1Ato 5, without the need to produce a special photo mask on which a formof a portion having partially increased width BW2 is reflected in orderto form the plurality of bit lines 750 having the partially increasedwidth BW2. This will now be described in more detail.

FIGS. 8A to 8H are sectional views illustrated in accordance with asequence of process steps to illustrate the method for forming a finepattern according to the third exemplary embodiment of the inventiveconcept.

Each of FIGS. 8A to 8H shows a structure corresponding to a sectionVIIIA-VIIIA′ and a section VIIIB-VIIIB′ of FIG. 7. In FIGS. 8A to 8H,like reference numerals in FIG. 7 denote like elements.

Referring to FIG. 8A, a conductive layer 830 for forming bit lines and ahard mask layer 840 are formed in order on a semiconductor substrate 800on which the plurality of word lines 710, the plurality of directcontacts 720, and planarized inter-layer insulation films 812 and 814are formed. Thereafter, a mask pattern 850 covering a portion of anupper surface 840T of the hard mask layer 840 is formed on the hard masklayer 840.

FIG. 9 is a layout illustrating a top view of the mask pattern 850.

Regarding the position of the mask pattern 850 formed on thesemiconductor substrate 800, FIG. 9 shows that a layout of the maskpattern 850 overlaps the layout of FIG. 7.

In FIG. 8A, the conductive layer 830 for forming bit lines may include ametal, e.g., tungsten. The hard mask layer 840 may include an oxidefilm, a nitride film, or a combination of them. The mask pattern 850 mayinclude photoresist materials or materials having a different etchingselectivity ratio from the hard mask layer 840.

Referring to FIG. 8B, a recess part 840R having a bottom surface 840U ata level lower than that of an upper surface 840T of the hard mask layer840 is formed by etching a portion from the exposed upper surface 840Tof the hard mask layer 840 using the mask pattern 850 as an etchingmask.

Referring to FIG. 8C, after removing the mask pattern 850 remaining onthe hard mask layer 840, an inorganic anti-reflection film 852 and anorganic anti-reflection film 860 are formed in order on the uppersurface 840T of the hard mask layer 840 and the bottom surface 840U ofthe recess part 840R. The inorganic anti-reflection film 852 and theorganic anti-reflection film 860 may be conformally formed on the hardmask layer 840 according to profiles of the upper surface 840T of thehard mask layer 840 and the bottom surface 840U of the recess part 840R.The inorganic anti-reflection film 852 may include SiON.

Due to a floor level difference between the upper surface 840T of thehard mask layer 840 and the bottom surface 840U of the recess part 840R,after the inorganic anti-reflection film 852 and the organicanti-reflection film 860 are formed, an upper surface of the organicanti-reflection film 860 has an upper surface profile in which a floorlevel difference exists between a first upper surface 860L at arelatively low level and a second upper surface 860H at a relativelyhigh level. Due to the floor level difference between the first uppersurface 860L and the second upper surface 860H, a distance from thesemiconductor substrate 800 to the first upper surface 860L is shorterthan that from the semiconductor substrate 800 to the second uppersurface 860H.

Referring to FIG. 8D, a photoresist film 870 is formed on the organicanti-reflection film 860 on which a floor level difference is formed dueto a level difference between the first upper surface 860L and thesecond upper surface 860H. The photoresist film 870 may include positivephotoresist materials.

The photoresist film 870 includes first areas 870F disposed on the firstupper surface 860L of the organic anti-reflection film 860 and secondareas 870D disposed on the second upper surface 860H of the organicanti-reflection film 860.

Referring to FIG. 8E, a partial area of the photoresist film 870 islight-exposed using a photo mask having a predetermined light exposurepattern.

In light exposure of the photoresist film 870, similarly as describedwith reference to FIG. 1F, there is applied a light exposure conditionin which an optimal focused electron beam is eradiated on the firstupper surface 860L of the organic anti-reflection film 860 and adefocused electron beam is eradiated on the second upper surface 860H ofthe organic anti-reflection film 860. To do this, an optimal focusposition in light exposure of the photoresist film 870 may be set to thefirst upper surface 860L of the organic anti-reflection film 860. Bydoing this, an optimal focused electron beam is eradiated on the firstarea 870F of the photoresist film 870, and a defocused electron beam iseradiated on the second area 870D of the photoresist film 870.

In a light exposure process described with reference to FIG. 8E, thephoto mask 200 on which the light exposure pattern 220, for example, isformed may be used as illustrated in FIG. 2. In this case, lightexposure areas 870E of the photoresist film 870 may be as illustrated inFIG. 8E.

FIG. 10 is a layout illustrating the light exposure areas 870E of thephotoresist film 870 when the photoresist film 870 is light-exposedusing the photo mask illustrated in FIG. 2.

Regarding the position of the light exposure areas 870E of thephotoresist film 870 on the semiconductor substrate 800, FIG. 10 showsthat the light exposure areas 870E of the photoresist film 870 overlapthe layout of FIG. 7.

In FIG. 10, the second area 870D disposed on the second upper surface860H of the organic anti-reflection film 860 out of the photoresist film870 is shown together. In the photoresist film 870, the light exposureareas 870E may extend in a direction orthogonal to an extended directionof the second area 870D. FIG. 10 illustrates a case in which the lightexposure areas 870E extend in an x direction, i.e., the same directionas an extended direction of each bit line 750, and the second area 870Dextends in a y direction, i.e., the same direction as an extendeddirection of each word line 710.

Referring to FIGS. 8E and 10, in the first area 870F on which an optimalfocused electron beam is eradiated out of the light exposure areas 870Eof the photoresist film 870, the electron beam in light exposure isevenly eradiated up to the bottom of the photoresist film 870 all overthe light exposure areas 870E. However, in the second area 870D on whicha defocused electron beam is eradiated out of the light exposure areas870E of the photoresist film 870, the electron beam in light exposure isnot evenly incident in the light exposure areas 870E because of arelatively poor focus due to the eradiation of the defocused electronbeam, and the closer from the top of the photoresist film 870 to thebottom thereof, the more areas 874 on which the electron beam is noteradiated in parts adjacent to non-light exposure areas 872 exist. Theareas 874 on which the electron beam is not eradiated may be areas underslopes represented with dotted lines in FIG. 8E.

Referring to FIG. 8F, the light-exposed photoresist film 870 isdeveloped. As a result, areas on which the electron beam is eradiatedare removed from the photoresist film 870, and a plurality ofphotoresist patterns 870A including the non-light exposure areas 872 ofthe photoresist film 870 and the areas 874 on which the electron beam isnot eradiated out of the light exposure areas 870E remain on the organicanti-reflection film 860.

Since the areas 874 on which the electron beam is not eradiated, whichremain in partial side walls of the non-light exposure areas 872, areincluded in partial areas of the plurality of photoresist patterns 870A,the plurality of photoresist patterns 870A have a form of lines, eachextending to have a variable width in a length direction (x direction inFIGS. 7, 9, and 10). In the plurality of photoresist patterns 870A, eachpart in which the areas 874 on which the electron beam is not eradiatedremain on the side walls of the non-light exposure areas 872 has a widthwider than that of each part in which only the non-light exposure areas872 exist.

Referring to FIG. 8G, a hard mask pattern 840A, an inorganicanti-reflection film pattern 852A, and an organic anti-reflection filmpattern 860A are formed by etching the organic anti-reflection film 860,the inorganic anti-reflection film 852, and the hard mask layer 840 inorder using the plurality of photoresist patterns 870A as an etchingmask.

While the hard mask pattern 840A is being formed, at least a portion ofthe plurality of photoresist patterns 870A may be attrited.

Referring to FIG. 8H, a plurality of conductive lines 830A are formed byetching the conductive layer 830 for forming bit lines using the hardmask pattern 840A as an etching mask. Thereafter, unnecessary filmsremaining on the plurality of conductive lines 830A are removed.

The plurality of conductive lines 830A may constitute the plurality ofbit lines 750 having a planar structure according to the layout of FIG.7.

The plurality of conductive lines 830A have a line form extending with avariable width in a length direction by including parts having a firstwidth MW1 of a relatively narrow width and parts having a second widthMW2 wider than the first width MW1.

The first width MW1 and the second width MW2 of the plurality ofconductive lines 830A may correspond to the line width BW1 and theincreased width BW2 of the plurality of bit lines 750 of FIG. 7,respectively.

Due to parts having the second width MW2 of a relatively wide width inthe plurality of conductive lines 830A, contact dimensions between eachdirect contact 720 and a corresponding conductive line 830A may beincreased in parts in which the plurality of conductive lines 830A andthe plurality of direct contacts 720 are connected to each other.

In the method for forming a fine pattern according to the thirdexemplary embodiment of the inventive concept described with referenceto FIGS. 7 to 10, in order to form the plurality of bit lines 750illustrated in FIG. 7, there is used a method for providing a floorlevel difference on the upper surface of the organic anti-reflectionfilm 860 formed on the hard mask layer 840 by etching a portion of thehard mask layer 840 to form a floor level difference for eradiating adefocused electron beam onto the photoresist film 870 in light exposure.However, various changes and modifications may be performed within thescope of the inventive concept. For example, in order to form a leveldifference structure covered by the photoresist film 870, instead of themethod for forming a floor level difference by etching the hard masklayer 840, a floor level difference for eradiating a defocused electronbeam on an upper surface of the inorganic anti-reflection film 852 maybe created by etching a portion of the inorganic anti-reflection film852 formed on the hard mask layer 840.

FIG. 11 is a layout of a plurality of fine patterns to be formed by amethod for forming a fine pattern according to a fourth exemplaryembodiment of the inventive concept.

FIG. 11 illustrates a case in which the plurality of fine patterns to beformed are a plurality of word lines formed in a core area or aperipheral circuit area of a semiconductor device.

Referring to FIG. 11, a plurality of active areas 910 are defined on asubstrate 900 on which by an isolation area 902. A plurality of wordlines 920A formed according to the method of the fourth exemplaryembodiment continuously extend in a constant direction (x direction inFIG. 11) over the active areas 910 and the isolation area 902 so as totraverse the active areas 910 and the isolation area 902.

High density of semiconductor devices results in active areas of thesemiconductor devices being decreased is size and a channel length oftransistors to be reduced in size. Accordingly, in order to control aHot Electron Induced Punch-through (HEIP) effect that may occur in anyof the boundaries between active areas and an isolation area, it isdesirable that a width of each word line be formed wider in acorresponding boundary between the active areas and the isolation area.

Therefore, each of the plurality of word lines 920A includes tabs 922protruded to both sides therefrom in a partial area disposed on eachboundary between the active areas 910 and the isolation area 902. Partsof the word lines 922A having the tabs 922 have a second width GW2 widerthan a first width GW1 of parts without the tabs 922.

In a case of producing a photo mask having a light exposure pattern of aform according to the layout of FIG. 11 to form the plurality of wordlines 920A including the tabs 922 and using the photo mask in a lightexposure process, there may appear a phenomenon that a pattern length isshorter than desired or an edge or corner part is rounded due to anoptical proximity effect as a pattern size is becoming increasinglyfiner. Due to this, in a case of embodying the plurality of word lines920A of FIG. 11 by means of a light exposure process using a photo maskproduced to have a light exposure pattern of a form according to thelayout of FIG. 11, it is difficult to secure a channel length as long asdesired in boundaries between the active areas 910 and the isolationarea 902.

In the inventive concept, depending on a form of a portion having thesecond width GW2 in order to form the plurality of word lines 920Ahaving the partially increased second width GW2 by including the tabs922, the plurality of word lines 920A having the second width GW2 may beformed in a similar fashion to the method for forming a fine patterndescribed with reference to FIGS. 1A to 5, without needing to produce aspecial photo mask. This will now be described in more detail.

FIGS. 12A to 12H are sectional views illustrated in accordance with asequence of process steps to describe the method for forming a finepattern according to the fourth exemplary embodiment of the inventiveconcept.

Each of FIGS. 12A to 12H shows a structure corresponding to a sectionXIIA-XIIA′ and a section XIIB-XIIB′ of FIG. 11. In FIGS. 12A to 12H,like reference numerals in FIG. 11 denote like elements.

Referring to FIG. 12A, a gate insulation film 912 and a conductive layer920 for forming word lines are formed in order on the semiconductorsubstrate 900 on which a plurality of active areas are defined by theisolation area 902.

The gate insulation film 912 may include a silicon oxide film, a siliconoxide nitride film, a high-k film consisting of a metal oxide, or acombination of them. The conductive layer 920 for forming word lines mayinclude a poly-silicon film, a metal film, a metal silicide film, or acombination of them.

Thereafter, a hard mask layer 940 is formed on the conductive layer 920for forming word lines, and a mask pattern 950 covering a portion of anupper surface 940T of the hard mask layer 940 is formed on the hard masklayer 940. The mask pattern 950 may include photoresist materials ormaterials having a different etching selectivity ratio from that of thehard mask layer 940.

Additional details of the hard mask layer 940 and the mask pattern 950are described in connection with the hard mask layer 840 and the maskpattern 850 described with reference to FIG. 8A.

FIG. 13 is a layout illustrating a top view of the mask pattern 950.

Regarding the position of the mask pattern 950 formed on thesemiconductor substrate 900, FIG. 13 shows that the layout of the maskpattern 950 overlaps the layout of FIG. 11.

Referring to FIG. 12B, a recess part 940R having a bottom surface 940Uof a level lower than that of the upper surface 940T of the hard masklayer 940 is formed by etching a portion from the exposed upper surface940T of the hard mask layer 940 using the mask pattern 950 as an etchingmask.

Referring to FIG. 12C, after removing the mask pattern 950 remaining onthe hard mask layer 940, an inorganic anti-reflection film 952 and anorganic anti-reflection film 960 are formed in order on the uppersurface 940T of the hard mask layer 940 and the bottom surface 940U ofthe recess part 940R. The inorganic anti-reflection film 952 and theorganic anti-reflection film 960 may be conformally formed on the hardmask layer 940 according to profiles of the upper surface 940T of thehard mask layer 940 and the bottom surface 940U of the recess part 940R.

Due to a floor level difference between the upper surface 940T of thehard mask layer 940 and the bottom surface 940U of the recess part 940R,after the inorganic anti-reflection film 952 and the organicanti-reflection film 960 are formed, an upper surface of the organicanti-reflection film 960 has an upper surface profile in which a floorlevel difference exists between a first upper surface 960L of arelatively low level and a second upper surface 960H of a relativelyhigh level. Due to the floor level difference between the first uppersurface 960L and the second upper surface 960H, a distance from thesemiconductor substrate 900 to the first upper surface 960L is shorterthan that from the semiconductor substrate 900 to the second uppersurface 960H.

Referring to FIG. 12D, a photoresist film 970 is formed on the organicanti-reflection film 960 on which a floor level difference is formed dueto a level difference between the first upper surface 960L and thesecond upper surface 960H. The photoresist film 970 may include positivephotoresist materials.

The photoresist film 970 includes a first area 970F disposed on thefirst upper surface 960L of the organic anti-reflection film 960 and asecond area 970D disposed on the second upper surface 960H of theorganic anti-reflection film 960.

Referring to FIG. 12E, a partial area of the photoresist film 970 islight-exposed by using a photo mask having a predetermined lightexposure pattern.

In light exposure of the photoresist film 970, similarly as describedwith reference to FIG. 1F, there is applied a light exposure conditionin which an optimal focused electron beam is eradiated on the firstupper surface 960L of the organic anti-reflection film 960 and adefocused electron beam is eradiated on the second upper surface 960H ofthe organic anti-reflection film 960. To do this, an optimal focusposition in light exposure of the photoresist film 970 may be set to thefirst upper surface 960L of the organic anti-reflection film 960. Bydoing this, an optimal focused electron beam is eradiated on the firstarea 970F of the photoresist film 970, and a defocused electron beam iseradiated on the second area 970D of the photoresist film 970.

FIG. 14 is a layout illustrating light exposure areas 970E of thephotoresist film 970 in the light exposure process described withreference to FIG. 12E.

Regarding the position of the light exposure areas 970E of thephotoresist film 970, FIG. 14 shows that the light exposure areas 970Eof the photoresist film 970 overlaps the layout of FIG. 11.

In FIG. 14, the second area 970D disposed on the second upper surface960H of the organic anti-reflection film 960 out of the photoresist film970 is shown together. In the photoresist film 970, the light exposureareas 970E may extend in a direction orthogonal to an extended directionof the second area 970D. FIG. 14 illustrates a case in which the lightexposure areas 970E extend in an x direction, and the second area 970Dextends in a y direction.

Referring to FIGS. 12E and 14, in the first area 970F on which anoptimal focused electron beam is eradiated out of the light exposureareas 970E of the photoresist film 970, the electron beam in lightexposure is evenly eradiated up to the bottom of the photoresist film970 all over the light exposure areas 970E. However, in the second area970D on which a defocused electron beam is eradiated out of the lightexposure areas 970E of the photoresist film 970, the electron beam inlight exposure is not evenly incident in the light exposure areas 970Ebecause of a relatively poor focus due to the eradiation of thedefocused electron beam, and the closer from the top of the photoresistfilm 970 to the bottom thereof, the more areas 974 on which the electronbeam is not eradiated in parts adjacent to non-light exposure areas 972exist. The areas 974 on which the electron beam is not eradiated may beareas under slopes represented with dotted lines in FIG. 12E.

Referring to FIG. 12F, the light-exposed photoresist film 970 isdeveloped. As a result, areas on which the electron beam is eradiatedare removed from the photoresist film 970, and a plurality ofphotoresist patterns 970A including the non-light exposure areas 972 ofthe photoresist film 970 and the areas 974 on which the electron beam isnot eradiated out of the light exposure areas 970E remain on the organicanti-reflection film 960.

Since the areas 974 on which the electron beam is not eradiated, whichremain in partial side walls of the non-light exposure areas 972, areincluded in partial areas of the plurality of photoresist patterns 970A,the plurality of photoresist patterns 970A have a form of lines, eachextending to have a variable width in a length direction (x direction inFIG. 14). In the plurality of photoresist patterns 970A, each part inwhich the areas 974 on which the electron beam is not eradiated remainon the side walls of the non-light exposure areas 972 has a width widerthan that of each part in which only the non-light exposure areas 972exist.

Referring to FIG. 12G, a hard mask pattern 940A, an inorganicanti-reflection film pattern 952A, and an organic anti-reflection filmpattern 960A are formed by etching the organic anti-reflection film 960,the inorganic anti-reflection film 952, and the hard mask layer 940 inorder using the plurality of photoresist patterns 970A as an etchingmask. While the hard mask pattern 940A is being formed, at least aportion of the plurality of photoresist patterns 970A may be attrited.

Referring to FIG. 12H, the plurality of word lines 920A and a gateinsulation film pattern 912A are formed by etching the conductive layer920 for forming word lines and the gate insulation film 912 using thehard mask pattern 940A as an etching mask. Thereafter, unnecessary filmsremaining on the plurality of word lines 920A are removed.

The plurality of word lines 920A have the planar structure shown in thelayout of FIG. 11.

The plurality of word lines 920A have a line form extending with avariable width in a length direction (x direction in FIG. 11) byincluding parts having the first width GW1 of a relatively narrow widthand parts having the second width GW2 wider than the first width GW1.

Due to parts having the second width GW2 of a relatively wide width inthe plurality of word lines 920A, a length of channels formed below theplurality of word lines 920A in the plurality of active areas 910 of thesemiconductor substrate 900 may be increased. As in the currentembodiment, by forming parts of the word lines 920A extending onboundaries between the plurality of active areas 910 and the isolationarea 902 to have the second width GW2 larger than the other parts, achannel length increases in the formed parts, thereby being able tocontrol the HEIP effect occurring in the boundaries between theplurality of active areas 910 and the isolation area 902.

In the method for forming a fine pattern according to the fourthexemplary embodiment of the inventive concept described with referenceto FIGS. 11 to 14, in order to form the plurality of word lines 920Aillustrated in FIG. 11, there is used a method for providing a floorlevel difference on the upper surface of the organic anti-reflectionfilm 960 formed on the hard mask layer 940 by etching a portion of thehard mask layer 940 to form a floor level difference for eradiating adefocused electron beam onto the photoresist film 970 in light exposure.However, various changes and modifications may be performed within thescope of the inventive concept. For example, in order to form a leveldifference structure covered by the photoresist film 970, instead of themethod for forming a floor level difference by etching the hard masklayer 940, a floor level difference for eradiating a defocused electronbeam on an upper surface of the inorganic anti-reflection film 952 maybe formed by etching a portion of the inorganic anti-reflection film 952formed on the hard mask layer 940.

FIG. 15 is a top view of a plurality of wiring patterns 1180 to beformed by a method for forming a fine pattern according to a fifthexemplary embodiment of the inventive concept.

The plurality of wiring patterns 1180 extend parallel to each other,each having a first width DW1. Each of the plurality of wiring patterns1180 has an increased second width DW2 in a partial area thereof.

FIGS. 16A to 16J are sectional views illustrated in accordance with asequence of process steps to illustrate the method for forming a finepattern according to the fifth exemplary embodiment of the inventiveconcept.

In the fifth exemplary embodiment to be described with reference toFIGS. 16A to 16J, a method for forming the plurality of wiring patterns1180 illustrated in FIG. 15 uses a damascene process. The plurality ofwiring patterns 1180 formed using the damascene process according to thecurrent exemplary embodiment may constitute a plurality of bit linesneeded to embody a semiconductor device or various kinds of metal wiringlayers to perform various functions.

Each of FIGS. 16A to 16J shows a structure corresponding to a sectionXVIA-XVIA′, a section XVIB-XVIB′, and a section XVIC-XVIC′ of FIG. 15.In FIGS. 16A to 16J, like reference numerals in FIG. 15 denote likeelements.

Referring to FIG. 16A, an etching stop layer 1102 is formed on asubstrate 1100 on which predetermined unit devices, e.g., a plurality ofword lines and an inter-layer insulation film covering them, are formed.A mold layer 1106 is formed on the etching stop layer 1102. The etchingstop layer 1102 may include, for example, a silicon nitride film, andthe mold layer 1106 may include, for example, an oxide film.

A hard mask layer 1140 is formed on the mold layer 1106. The hard masklayer 1140 may include materials having a different etching selectivityratio from that of the mold layer 1106. For example, when the mold layer1106 includes an oxide film, the hard mask layer 1140 may include anitride film or a poly-silicon film.

A mask pattern 1150 covering a portion of an upper surface 1140T of thehard mask layer 1140 is formed on the hard mask layer 1140. The maskpattern 1150 may include photoresist materials or materials having adifferent etching selectivity ratio from that of the hard mask layer1140.

FIG. 17 is a layout illustrating a top view of the mask pattern 1150.

Regarding the position of the mask pattern 1150 formed on thesemiconductor substrate 1100, FIG. 17 shows that the layout of the maskpattern 1150 overlaps the layout of the FIG. 15.

Referring to FIG. 16B, a recess part 1140R having a bottom surface 1140Uof a level lower than that of the upper surface 1140T of the hard masklayer 1140 is formed by etching a portion from the exposed upper surface1140T of the hard mask layer 1140 using the mask pattern 1150 as anetching mask.

Referring to FIG. 16C, after removing the mask pattern 1150 remaining onthe hard mask layer 1140, an inorganic anti-reflection film 1152 and anorganic anti-reflection film 1160 are formed in order on the uppersurface 1140T of the hard mask layer 1140 and the bottom surface 1140Uof the recess part 1140R. The inorganic anti-reflection film 1152 andthe organic anti-reflection film 1160 may be conformally formed on thehard mask layer 1140 according to profiles of the upper surface 1140T ofthe hard mask layer 1140 and the bottom surface 1140U of the recess part1140R.

Due to a floor level difference between the upper surface 1140T of thehard mask layer 1140 and the bottom surface 1140U of the recess part1140R, even after the inorganic anti-reflection film 1152 and theorganic anti-reflection film 1160 are formed, an upper surface of theorganic anti-reflection film 1160 has an upper surface profile in whicha floor level difference exists between a first upper surface 1160L of arelatively low level and a second upper surface 1160H of a relativelyhigh level. Due to the floor level difference between the first uppersurface 1160L and the second upper surface 1160H, a distance from thesemiconductor substrate 1100 to the first upper surface 1160L is shorterthan that from the semiconductor substrate 1100 to the second uppersurface 1160H.

Referring to FIG. 16D, a photoresist film 1170 is formed on the organicanti-reflection film 1160 on which a floor level difference is formeddue to a level difference between the first upper surface 1160L and thesecond upper surface 1160H. The photoresist film 1170 may includepositive photoresist materials.

The photoresist film 1170 includes a first area 1170F disposed on thefirst upper surface 1160L of the organic anti-reflection film 1160 and asecond area 1170D disposed on the second upper surface 1160H of theorganic anti-reflection film 1160.

Referring to FIG. 16E, a partial area of the photoresist film 1170 islight-exposed using a photo mask having a predetermined light exposurepattern.

In light exposure of the photoresist film 1170, similarly as describedwith reference to FIG. 1F, there is applied a light exposure conditionin which an optimal focused electron beam is eradiated on the firstupper surface 1160L of the organic anti-reflection film 1160 and adefocused electron beam is eradiated on the second upper surface 1160Hof the organic anti-reflection film 1160. To do this, an optimal focusposition in light exposure of the photoresist film 1170 may be set tothe first upper surface 1160L of the organic anti-reflection film 1160.By doing this, an optimal focused electron beam is eradiated on thefirst area 1170F of the photoresist film 1170, and a defocused electronbeam is eradiated on the second area 1170D of the photoresist film 1170.

FIG. 18 is a layout illustrating light exposure areas 1170E of thephotoresist film 1170 in the light exposure process described withreference to FIG. 16E.

Regarding the position of the light exposure areas 1170E of thephotoresist film 1170, FIG. 18 shows that the light exposure areas 1170Eof the photoresist film 1170 overlaps the layout of FIG. 15.

In FIG. 18, the second area 1170D disposed on the second upper surface1160H of the organic anti-reflection film 1160 out of the photoresistfilm 1170 is shown together.

Referring to FIGS. 16E and 18, in the first area 1170F on which anoptimal focused electron beam is eradiated out of the light exposureareas 1170E of the photoresist film 1170, the electron beam in lightexposure is evenly eradiated up to the bottom of the photoresist film1170 all over the light exposure areas 1170E. However, in the secondarea 1170D on which a defocused electron beam is eradiated out of thelight exposure areas 1170E of the photoresist film 1170, the electronbeam in light exposure is not evenly incident in the light exposureareas 1170E because of a relatively poor focus due to the eradiation ofthe defocused electron beam, and the closer from the top of thephotoresist film 1170 to the bottom thereof, the more areas 1174 onwhich the electron beam is not eradiated in parts adjacent to non-lightexposure areas 1172 exist. The areas 1174 on which the electron beam isnot eradiated may be areas under slopes represented with dotted lines inFIG. 16E.

Referring to FIG. 16F, the light-exposed photoresist film 1170 isdeveloped. As a result, areas on which the electron beam is eradiatedare removed from the photoresist film 1170, and a plurality ofphotoresist patterns 1170A including the non-light exposure areas 1172of the photoresist film 1170 and the areas 1174 on which the electronbeam is not eradiated out of the light exposure areas 1170E remain onthe organic anti-reflection film 1160.

Since the areas 1174 on which the electron beam is not eradiated, whichremain in partial side walls of the non-light exposure areas 1172, areincluded in partial areas of the plurality of photoresist patterns1170A, the plurality of photoresist patterns 870A have a form of lines,each extending to have a variable width in a length direction (ydirection in FIG. 18).

FIG. 19 is a top view of a result after the plurality of photoresistpatterns 1170A are formed.

In FIGS. 16F and 19, in the plurality of photoresist patterns 1170A,each part in which the areas 1174 on which the electron beam is noteradiated remain on the side walls of the non-light exposure areas 1172has a width wider than that of each part in which only the non-lightexposure areas 1172 exist.

Referring to FIG. 16G, a hard mask pattern 1140A, an inorganicanti-reflection film pattern 1152A, and an organic anti-reflection filmpattern 1160A are formed by etching the organic anti-reflection film1160, the inorganic anti-reflection film 1152, and the hard mask layer1140 in order using the plurality of photoresist patterns 1170A as anetching mask. While the hard mask pattern 1140A is being formed, atleast a portion of the plurality of photoresist patterns 1170A may beattrited.

Referring to 16H, a plurality of mold patterns 1106A and a plurality ofetching stop layer patterns 1102A are formed by etching the mold layer1106 using the hard mask pattern 1140A as an etching mask and using theetching stop layer 1102 as an etching end point.

A first space S1 of the relatively narrow first width MW1 and a secondspace S2 of the relatively wide second width MW2 are formed between eachtwo of the plurality of mold patterns 1106A, and an upper surface of thesubstrate 1100 is exposed through the first space S1 and the secondspace S2. The portion of the substrate 1100 exposed through the firstspace S1 and the second space S2 may be a conductive area included inthe substrate 1100.

After the plurality of mold patterns 1106A are formed, residual layersof the hard mask pattern 1140A may remain on the plurality of moldpatterns 1106A.

Referring to FIG. 161, the plurality of wiring patterns 1180 are formedon the substrate 1100 by forming a conductive layer filling the firstspace S1 and the second space S2 between the plurality of mold patterns1106A by means of the damascene process.

The plurality of wiring patterns 1180 have the planar structure shown inthe layout of FIG. 15.

The plurality of wiring patterns 1180 have a form of lines, eachextending to have a variable width in a length direction (y direction inFIG. 15). A portion having the relatively wide second width DW2 out ofthe plurality of wiring patterns 1180 is disposed under areas on whichan optimal focused electron beam is eradiated on the substrate 1100. Onthe other hand, a portion having the relatively narrow first width DW1out of the plurality of wiring patterns 1180 is disposed under areas onwhich a defocused electron beam is eradiated on the substrate 1100.

A detailed process for forming the plurality of wiring patterns 1180 bymeans of the damascene process will now be illustrated. A barrier filmis formed on the inner walls of the first and second spaces S1 and S2and the surface of the plurality of mold patterns 1106A. A metal filmfully filling the first and second spaces S1 and S2 is formed on thebarrier film. The barrier film is formed, for example, to prevent metalatoms of the metal film filling the first and second spaces S1 and S2from diffusing other films surrounding the metal film. A process offorming the barrier film is not a requisite process in the inventiveconcept and may be omitted in some cases. The metal film may include anyof Cu, W, and Al. For example, the metal film may include Cu havingrelatively low resistivity. In order to form the metal film, a PhysicalVapor Deposition (PVD) process or an electroplating process may be used.Thereafter, by removing a portion of the metal film and a portion of thebarrier film until upper surfaces of the plurality of mold patterns1106A are exposed, the plurality of wiring patterns 1180 including thebarrier film and the metal film are formed within the first space S1 andthe second space S2 between the plurality of mold patterns 1106A.

Referring to FIG. 16J, the plurality of mold patterns 1106A and theplurality of etching stop layer patterns 1102A are removed. In somecases, the process of FIG. 16J may be omitted.

In the method for forming a fine pattern according to the fifthexemplary embodiment of the inventive concept described with referenceto FIGS. 15 to 19, in order to form the plurality of mold patterns 1106Aneeded to form the plurality of wiring patterns 1180 illustrated in FIG.15 by means of the damascene process, there is used a method forproviding a floor level difference on the upper surface of the organicanti-reflection film 1160 formed on the hard mask layer 1140 by etchinga portion of the hard mask layer 1140 to form a floor level differencefor eradiating a defocused electron beam onto the photoresist film 1170in light exposure. However, various changes and modifications may beperformed within the scope of the inventive concept. For example, inorder to form a level difference structure covered by the photoresistfilm 1170, instead of the method for forming a floor level difference byetching the hard mask layer 1140, a floor level difference foreradiating a defocused electron beam on an upper surface of theinorganic anti-reflection film 1152 may be created by etching a portionof the inorganic anti-reflection film 1152 formed on the hard mask layer1140. Alternatively, if a process of forming the hard mask layer 1140 isomitted, a floor level difference for eradiating a defocused electronbeam on an upper surface of the mold layer 1106 may be created byetching a portion of the mold layer 1106.

While the inventive concept has been particularly shown and describedwith reference to exemplary embodiments thereof, it will be understoodthat various changes in form and details may be made therein withoutdeparting from the spirit and scope of the following claims.

1. A method for forming a fine pattern, the method comprising: forming afirst film on a substrate; forming a first film pattern including afirst level area and a second level area having different distances fromthe substrate by changing a profile of an upper surface of the firstfilm; forming a photoresist film having a first area covering the firstlevel area and a second area covering the second level area;light-exposing the photoresist film under a light exposure condition, inwhich an optimal focused electron beam is eradiated on the first areaand a defocused electron beam is eradiated on the second area, by usinga photo mask having a light exposure pattern for simultaneouslylight-exposing the first area and the second area with the same width;forming a plurality of photoresist patterns continuously extending overthe first level area and the second level area of the first film patternwith different widths on the first level area and the second level areaby developing the light-exposed photoresist film; and forming aplurality of first fine patterns having different widths on the firstlevel area and the second level area by etching the first film patternusing the plurality of photoresist patterns as an etching mask.
 2. Themethod of claim 1, wherein the forming a first film pattern comprises:forming a mask pattern covering an upper surface of the first film;forming a recess part with a bottom surface having a level lower thanthat of the upper surface of the first film by etching a portion of thefirst film from the upper surface of the first film using the maskpattern as an etching mask; and exposing an upper surface of the firstfilm pattern by removing the mask pattern.
 3. The method of claim 2,wherein the bottom surface of the recess part is disposed in the firstlevel area, and the upper surface of the first film pattern is disposedin the second level area.
 4. The method of claim 2, wherein the bottomsurface of the recess part is disposed in the second level area, and theupper surface of the first film pattern is disposed in the first levelarea.
 5. The method of claim 1, further comprising forming a second filmhaving an upper surface with a floor level difference on the first filmpattern before forming the photoresist film and after forming the firstfilm pattern, wherein the photoresist patterns is formed on the secondfilm.
 6. The method of claim 5, wherein the second film is a singlefilm.
 7. The method of claim 5, wherein the second film is a multiplefilm in which a plurality of films are layered in order.
 8. The methodof claim 1, wherein a plurality of first level areas are formed on theupper surface of the first film pattern, and the first level area has aplanar structure of a form of a plurality of lines extending parallel toeach other.
 9. The method of claim 1, wherein a plurality of first levelareas are formed on the upper surface of the first film pattern, andeach of the plurality of first level areas has a planar structure of oneof a circle, an ellipse, and a polygon.
 10. The method of claim 1,wherein the substrate comprises a first member layer exposed on an uppersurface thereof, and the method further comprises forming a first memberpattern having a variable width in a length direction by etching thefirst member layer using the first fine pattern as an etching mask afterforming the first fine pattern.
 11. The method of claim 10, wherein thefirst member layer includes an insulation film or a conductive film.